Differential cell analysis of cytocentrifuged bronchoalveolar fluid samples affected by the area counted

OBJECTIVE: To investigate variations in the differential cell counts betwee n the quadrants of cytocentrifuged bronchoalveolar lavage (BAL) fluid prepa rations and to evaluate the diagnostic impact of these differences in inter stitial lung diseases (ILD). STUDY DESIGN: BAL fluid samples obtained from 30 patients suspected of havi ng ILD or pneumonia were cytocentuifuged and additionally stained with May- Grunwald-Giemsa stain. Two observers differentiated 200 cells in each quadr ant as well as in a circular pattern around the center of the cytocentrifug e spot. RESULTS: Lymphocytes and alveolar macrophages Ic,ere not randomly distribut ed on the cytocentrifirge spot. Ten samples of patients with histologically confirmed ILD were selected to test the diagnostic impact using a validate d computer program. The predicted diagnosis did not correspond to the histo logic diagnosis for one quadrant from 1 of these 10 samples (sarcoidosis in stead of idiopathic pulmonary fibrosis), whereas the differential cell coun ts performed around the center of the cytocentrifuge spot provided the corr ect diagnosis in all cases. CONCLUSION: BAL fluid differential cell counts varied between the quadrants of the cytocentrifuge spot. The center of the cytocentrifuge spot appeared to be the most reliable area. Therefore, cell counting is recommended in a circular pattern around the center of the cytocentrifuge spot.